#include <stdio.h>
int fei(int sn) {
	if(sn<=1) {
		return 1;
	}
	return fei(sn - 2) + fei(sn - 1);
}
int main() {
	int sn = 0;
	printf("请输入一个数：");
	scanf("%d",&sn);
	printf("%d\n",fei(sn));
	return 0;
}
